The use of valving to control fluid flow has countless applications. One type of common line valve is the Y pattern globe valve which has an inlet passage, an outlet passage and a control stem passage containing the valve stem movable within the body of the valve with the passages generally intersecting in a Y pattern. The movable valve stem will typically have sealing structure which moves into sealing engagement with a portion of the valve body to stop flow between the inlet and outlet passages when the valve is to be closed. The valve stem can be retracted to permit flow between the inlet and outlet passages to open the valve.
A large number of valves, including the Y pattern globe valve, employ soft seals to act between a valve stem and valve body seat. In high pressure applications, particularly in flow of high pressure gas in the 6000 psi range, as the valve stem moves toward the valve body seat, the soft seal typically is extruded outward and under the retaining element retaining the soft seal on the valve stem. This extrusion causes small amounts of the soft seal to be sheared off with each open and close cycle. This shearing activity reduces the volume of the seal over time, which can result in leaking due to improper contact with the valve body seat, and even a seal blowout.
A need exists to develop a valve having a seal which is not extruded during each cycle of the valve between the open and closed position. This need becomes particularly acute when the valve is in a high pressure gas line having maximum pressures of approximately 6000 psi and above.